System and method for continuous separation of isotopes

Abstract

The invention is both a system and method for continuously separating heavier from lighter isotopes of a particular element, such as zirconium. The system comprises a housing, a column assembly rotatably mounted with respect to the housing which includes a plurality of vertically oriented separation cells arranged in a circle, each of which contains a packing material, both a feed electrolyte source and a barren electrolyte source, each of which has an outlet mounted in the housing for continuously introducing either a feed electrolyte or a barren electrolyte into each of the cells as they rotate past the outlets, and upper and lower electrodes disposed over the upper and lower ends of the separation cells for inducing the electromigration of the lighter zirconium ions toward the lower ends of each of the separation cells. A drain assembly disposed beneath the column assembly continuously collects isotopic enriched electrolyte from the bottom ends of the separation cells. The speed of rotation of the column assembly is coordinated with the rate of eluant flow through the cells so that the same segments of the annular tray of the drain assembly continuously collect eluant enriched in a particular type of zirconium isotope.

I claim: 
     
       1. An isotopic separation system for continuously separating the isotopes present in a sample containing a mixture of isotopes of a chemical element in ionic form, said system comprising: (a) rotatable annulus means having a feed end spaced axially from a discharge end for holding a plurality of circumferentially spaced separation cell means packed with a separation medium for separating said isotopes, wherein each of said separation cell means extends axially from said feed end to said discharge end;   (b) an isotope-containing sample feed source having an outlet means for introducing said sample into each of said separation cell means;   (c) an eluant source having a plurality of outlet means, wherein each said outlet means corresponds to a separation cell means, for introducing eluant into each said separation cell means;   (d) a pair of annular electrode means, one of said pair being located at the feed end of said annulus means and the other of said pair being located at the discharge end of said annulus means, for applying an electric potential axially along said annulus means and each of said separation cell means while said annulus means is rotating, thereby causing the separation of lighter isotopes from heavier isotopes in said sample and the enrichment of said eluant with said isotopes; and   (d) drain assembly means at the discharge end of said annulus means for continuously collecting eluant enriched with one of said isotopes, including discharge outlet means associated with each said separation cell means for withdrawing isotopically enriched eluant from each said cell separation means.   
     
     
       2. A system as defined in claim 1 wherein each of said separation cell means further includes a drain port located at its discharge end, and said drain assembly means includes an annular collection tray which is uniformly partitioned around its circumference into as many collection segments as there are separation cell means, and wherein the discharge outlet means of said separation cell means are registrable with segments of said collection tray. 
     
     
       3. A system as defined in claim 2, wherein each of said segments of said collection tray includes a drain conduit for draining electrolyte collected in said segment. 
     
     
       4. A system as defined in claim 1, wherein each said annular electrode means includes a conductor disposed over the feed and discharge ends of said annulus means. 
     
     
       5. A system as defined in claim 4, wherein each of said conductors is covered by an electrically insulative material, and wherein each conductor includes an opening over each of the feed and discharge separation cell means for conducting eluant through said separation cell means. 
     
     
       6. An isotopic separation system as described in claim 1, wherein said separation medium is selected from the group consisting of cation exchange resins, anion exchange resins, size exclusion media and reverse phase packing. 
     
     
       7. An isotopic separation system as described in claim 1, wherein each said separation cell means is defined by a pair of circumferentially spaced, axially extending impermeable partitions within said annulus means. 
     
     
       8. An isotopic separation system as described in claim 7, further including rotary drive means for rotating said annulus means at a predetermined speed relative to said sample feed source outlet means, said eluant source outlet means and said drain assembly means, wherein said speed is selected to cause isotopically enriched eluant from a selected one of said separation cell means to be discharged at substantially the same location in said drain assembly means. 
     
     
       9. An isotopic separation system for continuously separating the zirconium isotopes present in a sample containing a mixture of isotopes of zirconium in ionic form, said system comprising: (a) rotatable annulus means having a feed end spaced axially from a discharge end for holding a plurality of circumferentially spaced separation cell means packed with a separation medium for separating said zirconium isotopes, wherein each of said separation cell means extends axially from said feed end to said discharge end;   (b) a zirconium isotope-containing sample feed source having an outlet means for introducing said sample into each of said separation cell means;   (c) an eluant source; having a plurality of outlet means, wherein each said outlet means corresponds to a separation cell means, for introducing eluant into each said separation cell means;   (d) a pair of annular electrode means, one of said pair being located at the feed end of said annulus means and the other of said pair being located at the discharge end of said annulus means, for applying an electric potential axially along said annulus means and each of said separation cell means while said annulus means is rotating, thereby causing the separation of lighter zirconium isotopes from heavier zirconium isotopes in said sample and the enrichment of said eluant with said zirconium isotopes; and   (e) drain assembly means at the discharge end of said annulus means for continuously collecting eluant enriched with one of said zirconium isotopes including discharge outlet means associated with each said separation cell means for withdrawing eluant enriched with one of said zirconium isotopes from each said cell separation means.   
     
     
       10. An isotopic separation system as described in claim 9, wherein said separation medium is selected from the group consisting of cation exchange resins, anion exchange resins, size exclusion media and reverse phase packing. 
     
     
       11. An isotopic separation system as described in claim 9, wherein each said separation cell means is defined by a pair of circumferentially spaced, axially extending impermeable partitions within said annulus means. 
     
     
       12. An isotopic separation system described in claim 11, further including rotary drive means for rotating said annulus means at a predetermined speed relative to said sample feed source outlet means, said eluant source outlet means and said drain assembly means, wherein said speed is selected to cause eluant enriched with a zirconium isotope from a selected one of said separation cell means to be discharged at substantially the same location in said drain assembly means. 
     
     
       13. A system for separating isotopes of zirconium present in a sample containing at least the isotopes zirconium-90, Zirconium-91, Zirconium-92, Zirconium-94 and Zirconium-96 in ionic form, said system comprising: (a) a plurality of axial separation cells spaced circumferentially between an outer wall and a concentric inner wall of a rotatable annulus and defined by impermeable partitions extending between said inner and outer wall, said separation cells being packed from a feed end to a discharge end with a separation medium;   (b) a source of said zirconium isotope-containing sample and a suitable electrolyte, said isotope source including an outlet whereby said sample is continuously introduced into the feed end of said separation cells;   (c) a source of an eluant electrolyte compatible with the suitable electrolyte, said eluant electrolyte source including a plurality of outlets corresponding to said plurality of separation cells whereby said eluant electrolyte is continuously introduced into the feed end of said separation cells;   (d) axial electric potential generating means including a first annular electrode positioned adjacent to the feed end of the separation cells, and a second annular electrode positioned adjacent to the discharge end of the separation cells for applying an electric potential axially between the feed end and the discharge end of the separation cells;   (e) rotary drive means for causing said annulus to rotate simultaneously while said electric potential is being applied; and   (f) zirconium isotope collection means including a drain assembly with a plurality of compartments corresponding to said plurality of compartments corresponding to said plurality of separation cells for collecting each of said separated isotopes.   
     
     
       14. The zirconium isotope separation system described in claim 13, wherein said separation medium is selected from the group consisting of cation exchange resins, anion exchange resins, size exclusion media and reverse phase packing. 
     
     
       15. The zirconium isotope separation system described in claim 14, wherein said separation medium is a cation exchange resin, the zirconium isotope-containing sample is zirconium chloride, and both the suitable electrolyte and the eluant electrolyte are hydrochloric acid.